| 1999-04-05 | vs TBA | 1 | W 10-7 | 0-1 | 3 | 46,733 | Mike Mussina | Wilson Alvarez | Mike Mussina | Wilson Alvarez | Mike Timlin | 10 | 7 | 3 |
| 1999-04-07 | vs TBA | 2 | L 5-8 | 0-2 | 5 | 42,284 | Juan Guzman | Tony Saunders | Tony Saunders | Juan Guzman | Roberto Hernandez | 15 | 15 | 0 |
| 1999-04-08 | vs TBA | 3 | L 3-6 | 0-3 | 5 | 39,853 | Scott Erickson | Bobby Witt | Bobby Witt | Scott Erickson | | 18 | 21 | -3 |
| 1999-04-09 | vs TOR | 4 | L 4-7 | 0-4 | 5 | 36,430 | Sidney Ponson | Kelvim Escobar | Kelvim Escobar | Sidney Ponson | | 22 | 28 | -6 |
| 1999-04-10 | vs TOR | 5 | W 1-0 | 1-4 | 5 | 43,700 | Mike Mussina | Chris Carpenter | Mike Mussina | Chris Carpenter | Mike Timlin | 23 | 28 | -5 |
| 1999-04-11 | vs TOR | 6 | L 5-9 | 1-5 | 5 | 40,273 | Doug Linton | Pat Hentgen | Roy Halladay | Jesse Orosco | | 28 | 37 | -9 |
| 1999-04-13 | @ NYA | 7 | L 3-6 | 1-6 | 5 | 25,254 | Juan Guzman | Ramiro Mendoza | Jeff Nelson | Arthur Rhodes | | 31 | 43 | -12 |
| 1999-04-14 | @ NYA | 8 | L 7-14 | 2-6 | 5 | 26,898 | Scott Erickson | David Cone | David Cone | Scott Erickson | | 38 | 57 | -19 |
| 1999-04-15 | @ NYA | 9 | W 9-7 | 3-6 | 5 | 30,958 | Mike Mussina | Roger Clemens | Arthur Rhodes | Mariano Rivera | Mike Timlin | 47 | 64 | -17 |
| 1999-04-16 | @ TOR | 10 | L 6-7 | 3-7 | 5 | 25,281 | Sidney Ponson | Pat Hentgen | Graeme Lloyd | Ricky Bones | Robert Person | 53 | 71 | -18 |
| 1999-04-17 | @ TOR | 11 | L 4-7 | 3-8 | 5 | 30,739 | Doug Linton | David Wells | David Wells | Doug Linton | Graeme Lloyd | 57 | 78 | -21 |
| 1999-04-18 | @ TOR | 12 | L 0-6 | 3-9 | 5 | 27,126 | Juan Guzman | Roy Halladay | Roy Halladay | Juan Guzman | | 57 | 84 | -27 |
| 1999-04-20 | @ TBA | 13 | L 3-5 | 3-10 | 5 | 17,660 | Scott Erickson | Julio Santana | Julio Santana | Scott Erickson | Roberto Hernandez | 60 | 89 | -29 |
| 1999-04-21 | @ TBA | 14 | L 8-14 | 4-10 | 5 | 22,119 | Mike Mussina | Bryan Rekar | Bryan Rekar | Mike Mussina | | 68 | 103 | -35 |
| 1999-04-22 | @ TBA | 15 | L 0-1 | 4-11 | 5 | 17,334 | Sidney Ponson | Tony Saunders | Tony Saunders | Sidney Ponson | Roberto Hernandez | 68 | 104 | -36 |
| 1999-04-23 | vs OAK | 16 | W 7-4 | 5-11 | 5 | 42,978 | Juan Guzman | Jimmy Haynes | Mike Fetters | Jimmy Haynes | | 75 | 108 | -33 |
| 1999-04-24 | vs OAK | 17 | L 0-3 | 5-12 | 5 | 41,540 | Scott Erickson | Mike Oquist | Mike Oquist | Scott Erickson | Billy Taylor | 75 | 111 | -36 |
| 1999-04-25 | vs OAK | 18 | L 10-11 | 5-13 | 5 | 45,675 | Rocky Coppinger | Kenny Rogers | Brad Rigby | Mike Timlin | Billy Taylor | 85 | 122 | -37 |
| 1999-04-27 | vs KCA | 19 | W 8-4 | 6-13 | 5 | 36,682 | Mike Mussina | Kevin Appier | Mike Mussina | Kevin Appier | Mike Timlin | 93 | 126 | -33 |
| 1999-04-28 | vs KCA | 20 | L 2-8 | 6-14 | 6 | 35,175 | Juan Guzman | Jose Rosado | Jose Rosado | Juan Guzman | | 95 | 134 | -39 |
| 1999-04-29 | vs KCA | 21 | L 5-15 | 7-14 | 5 | 34,347 | Scott Erickson | Jeff Suppan | Jeff Suppan | Scott Erickson | Jose Santiago | 100 | 149 | -49 |
| 1999-04-30 | vs MIN | 22 | W 7-1 | 8-14 | 5 | 41,688 | Sidney Ponson | LaTroy Hawkins | Sidney Ponson | LaTroy Hawkins | | 107 | 150 | -43 |
| 1999-05-01 | vs MIN | 23 | L 2-7 | 8-15 | 5 | 44,054 | Rocky Coppinger | Brad Radke | Brad Radke | Rocky Coppinger | | 109 | 157 | -48 |
| 1999-05-02 | vs MIN | 24 | W 6-0 | 9-15 | 5 | 41,535 | Mike Mussina | Eric Milton | Mike Mussina | Eric Milton | | 115 | 157 | -42 |
| 1999-05-04 | vs CHA | 25 | W 9-5 | 10-15 | 5 | 37,846 | Scott Erickson | Mike Sirotka | Mike Timlin | David Lundquist | | 124 | 162 | -38 |
| 1999-05-05 | vs CHA | 26 | W 8-0 | 11-15 | 5 | 40,081 | Juan Guzman | Jaime Navarro | Juan Guzman | Jaime Navarro | | 132 | 162 | -30 |
| 1999-05-06 | vs CHA | 27 | W 4-2 | 12-15 | 5 | 36,880 | Sidney Ponson | James Baldwin | Sidney Ponson | James Baldwin | Mike Timlin | 136 | 164 | -28 |
| 1999-05-07 | @ DET | 28 | W 9-4 | 13-15 | 5 | 15,519 | Mike Mussina | Justin Thompson | Mike Mussina | Justin Thompson | | 145 | 168 | -23 |
| 1999-05-08 | @ DET | 29 | L 6-7 | 13-16 | 5 | 18,068 | Scott Kamieniecki | Willie Blair | Willie Blair | Scott Kamieniecki | Todd Jones | 151 | 175 | -24 |
| 1999-05-09 | @ DET | 30 | W 5-0 | 14-16 | 5 | 16,940 | Scott Erickson | Dave Mlicki | Scott Erickson | Dave Mlicki | | 156 | 175 | -19 |
| 1999-05-10 | @ CLE | 31 | L 4-6 | 14-17 | 5 | 40,615 | Juan Guzman | Dave Burba | Dave Burba | Juan Guzman | Michael Jackson | 160 | 181 | -21 |
| 1999-05-11 | @ CLE | 32 | L 6-11 | 15-17 | 5 | 40,587 | Sidney Ponson | Bartolo Colon | Bartolo Colon | Sidney Ponson | | 166 | 192 | -26 |
| 1999-05-12 | @ CLE | 33 | L 5-6 | 15-18 | 5 | 42,939 | Mike Mussina | Dwight Gooden | Paul Assenmacher | Mike Timlin | Paul Shuey | 171 | 198 | -27 |
| 1999-05-13 | @ TEX | 34 | L 7-15 | 16-18 | 4 | 40,678 | Scott Kamieniecki | Mike Morgan | Mike Morgan | Scott Kamieniecki | | 178 | 213 | -35 |
| 1999-05-14 | @ TEX | 35 | L 6-7 | 16-19 | 4 | 36,665 | Scott Erickson | Mark Clark | Tim Crabtree | Arthur Rhodes | John Wetteland | 184 | 220 | -36 |
| 1999-05-15 | @ TEX | 36 | L 1-8 | 16-20 | 5 | 46,118 | Juan Guzman | Rick Helling | Rick Helling | Doug Johns | | 185 | 228 | -43 |
| 1999-05-16 | @ TEX | 37 | W 16-5 | 16-21 | 5 | 39,508 | Sidney Ponson | Aaron Sele | Sidney Ponson | Aaron Sele | | 201 | 233 | -32 |
| 1999-05-18 | vs ANA | 38 | W 5-3 | 17-21 | 5 | 42,830 | Mike Mussina | Chuck Finley | Mike Mussina | Chuck Finley | Mike Timlin | 206 | 236 | -30 |
| 1999-05-19 | vs ANA | 39 | L 4-5 | 17-22 | 5 | 38,557 | Scott Erickson | Omar Olivares | Al Levine | Mike Timlin | Troy Percival | 210 | 241 | -31 |
| 1999-05-20 | vs ANA | 40 | L 4-6 | 17-23 | 5 | 38,388 | Jason Johnson | Tim Belcher | Tim Belcher | Jason Johnson | Troy Percival | 214 | 247 | -33 |
| 1999-05-21 | vs TEX | 41 | W 3-2 | 18-23 | 5 | 45,867 | Sidney Ponson | Rick Helling | Sidney Ponson | Rick Helling | | 217 | 249 | -32 |
| 1999-05-22 | vs TEX | 42 | L 7-8 | 18-24 | 6 | 47,915 | Juan Guzman | Aaron Sele | Tim Crabtree | Mike Timlin | John Wetteland | 224 | 257 | -33 |
| 1999-05-23 | vs TEX | 43 | W 15-6 | 18-25 | 5 | 40,516 | Mike Mussina | Mike Morgan | Mike Mussina | Mike Morgan | | 239 | 263 | -24 |
| 1999-05-25 | @ ANA | 44 | L 1-4 | 18-26 | 5 | 20,398 | Scott Erickson | Omar Olivares | Omar Olivares | Scott Erickson | Troy Percival | 240 | 267 | -27 |
| 1999-05-26 | @ ANA | 45 | W 3-2 | 19-26 | 5 | 22,058 | Sidney Ponson | Tim Belcher | Sidney Ponson | Tim Belcher | Arthur Rhodes | 243 | 269 | -26 |
| 1999-05-27 | @ ANA | 46 | W 6-3 | 20-26 | 4 | 24,724 | Juan Guzman | Ken Hill | Juan Guzman | Ken Hill | Mike Timlin | 249 | 272 | -23 |
| 1999-05-28 | @ OAK | 47 | L 1-2 | 20-27 | 4 | 7,443 | Mike Mussina | Tom Candiotti | Tom Candiotti | Mike Mussina | Billy Taylor | 250 | 274 | -24 |
| 1999-05-29 | @ OAK | 48 | W 7-5 | 21-27 | 4 | 26,247 | Jason Johnson | Gil Heredia | Doug Johns | T.J. Mathews | Arthur Rhodes | 257 | 279 | -22 |
| 1999-05-30 | @ OAK | 49 | L 5-11 | 22-27 | 4 | 18,320 | Scott Erickson | Mike Oquist | Brad Rigby | Scott Erickson | | 262 | 290 | -28 |
| 1999-05-31 | @ SEA | 50 | L 6-10 | 23-27 | 4 | 23,100 | Sidney Ponson | Jamie Moyer | Jamie Moyer | Sidney Ponson | Jose Mesa | 268 | 300 | -32 |
| 1999-06-01 | @ SEA | 51 | W 14-11 | 24-27 | 4 | 21,597 | Juan Guzman | Freddy Garcia | Doug Johns | Freddy Garcia | | 282 | 311 | -29 |
| 1999-06-02 | @ SEA | 52 | L 2-4 | 24-28 | 4 | 21,651 | Mike Mussina | John Halama | Jose Paniagua | Mike Mussina | Jose Mesa | 284 | 315 | -31 |
| 1999-06-04 | vs PHI | 53 | L 5-9 | 24-29 | 4 | 47,542 | Scott Erickson | Chad Ogea | Chad Ogea | Scott Erickson | | 289 | 324 | -35 |
| 1999-06-05 | vs PHI | 54 | W 7-6 | 25-29 | 4 | 48,531 | Sidney Ponson | Carlton Loewer | Mike Timlin | Steve Montgomery | | 296 | 330 | -34 |
| 1999-06-06 | vs PHI | 55 | L 7-11 | 26-29 | 4 | 47,833 | Juan Guzman | Robert Person | Joel Bennett | Ricky Bones | | 303 | 341 | -38 |
| 1999-06-08 | @ FLO | 56 | L 1-2 | 26-31 | 5 | 0 | Mike Mussina | Ryan Dempster | Brian Edmondson | Mike Timlin | | 304 | 343 | -39 |
| 1999-06-08 | @ FLO | 57 | L 3-5 | 26-31 | 5 | 13,003 | Jason Johnson | Alex Fernandez | Antonio Alfonseca | Scott Kamieniecki | Matt Mantei | 307 | 348 | -41 |
| 1999-06-09 | @ FLO | 58 | W 4-2 | 27-31 | 4 | 12,851 | Scott Erickson | Dennis Springer | Scott Erickson | Dennis Springer | Arthur Rhodes | 311 | 350 | -39 |
| 1999-06-11 | @ ATL | 59 | W 6-2 | 28-31 | 4 | 47,428 | Sidney Ponson | Greg Maddux | Sidney Ponson | Greg Maddux | | 317 | 352 | -35 |
| 1999-06-12 | @ ATL | 60 | W 5-0 | 29-31 | 4 | 47,923 | Juan Guzman | Kevin Millwood | Juan Guzman | Kevin Millwood | | 322 | 352 | -30 |
| 1999-06-13 | @ ATL | 61 | W 22-1 | 30-31 | 4 | 45,738 | Mike Mussina | John Smoltz | Mike Mussina | John Smoltz | | 344 | 353 | -9 |
| 1999-06-14 | vs KCA | 62 | W 7-1 | 31-31 | 4 | 37,501 | Scott Erickson | Kevin Appier | Scott Erickson | Kevin Appier | | 351 | 354 | -3 |
| 1999-06-15 | vs KCA | 63 | W 6-5 | 32-31 | 4 | 41,377 | Jason Johnson | Chris Fussell | Mike Timlin | Scott Service | | 357 | 359 | -2 |
| 1999-06-16 | vs KCA | 64 | W 2-1 | 33-31 | 4 | 41,913 | Sidney Ponson | Jose Rosado | Sidney Ponson | Jose Rosado | | 359 | 360 | -1 |
| 1999-06-17 | @ CHA | 65 | L 3-9 | 33-32 | 4 | 16,496 | Juan Guzman | Mike Sirotka | Mike Sirotka | Juan Guzman | Keith Foulke | 362 | 369 | -7 |
| 1999-06-18 | @ CHA | 66 | W 3-2 | 34-32 | 4 | 17,098 | Mike Mussina | Jaime Navarro | Mike Mussina | Jaime Navarro | | 365 | 371 | -6 |
| 1999-06-19 | @ CHA | 67 | W 11-9 | 34-33 | 4 | 30,232 | Scott Erickson | John Snyder | Arthur Rhodes | Keith Foulke | Scott Kamieniecki | 376 | 380 | -4 |
| 1999-06-20 | @ CHA | 68 | W 8-4 | 35-33 | 4 | 22,755 | Jason Johnson | James Baldwin | Jason Johnson | James Baldwin | Mike Timlin | 384 | 384 | 0 |
| 1999-06-22 | vs BOS | 69 | W 5-3 | 36-33 | 4 | 43,329 | Sidney Ponson | Pat Rapp | Arthur Rhodes | Mark Guthrie | Mike Timlin | 389 | 387 | 2 |
| 1999-06-23 | vs BOS | 70 | L 0-5 | 36-34 | 4 | 45,086 | Juan Guzman | Bret Saberhagen | Bret Saberhagen | Juan Guzman | | 389 | 392 | -3 |
| 1999-06-24 | vs BOS | 71 | L 1-2 | 36-35 | 4 | 47,388 | Mike Mussina | Mark Portugal | Mark Portugal | Mike Mussina | Tim Wakefield | 390 | 394 | -4 |
| 1999-06-25 | vs NYA | 72 | L 8-9 | 36-36 | 4 | 47,936 | Scott Erickson | Hideki Irabu | Dan Naulty | Mike Timlin | Mariano Rivera | 398 | 403 | -5 |
| 1999-06-26 | vs NYA | 73 | L 4-7 | 36-37 | 4 | 47,841 | Jason Johnson | David Cone | David Cone | Jason Johnson | Mariano Rivera | 402 | 410 | -8 |
| 1999-06-27 | vs NYA | 74 | L 2-6 | 36-38 | 4 | 48,020 | Sidney Ponson | Orlando Hernandez | Orlando Hernandez | Sidney Ponson | | 404 | 416 | -12 |
| 1999-06-29 | @ TOR | 75 | L 5-6 | 36-39 | 4 | 21,421 | Juan Guzman | Pat Hentgen | John Frascatore | Arthur Rhodes | | 409 | 422 | -13 |
| 1999-06-30 | @ TOR | 76 | L 9-10 | 37-39 | 4 | 21,137 | Mike Mussina | David Wells | John Frascatore | Jesse Orosco | | 418 | 432 | -14 |
| 1999-07-01 | @ TOR | 77 | L 6-8 | 37-40 | 4 | 30,263 | Scott Erickson | Joey Hamilton | John Frascatore | Mike Timlin | Billy Koch | 424 | 440 | -16 |
| 1999-07-02 | @ NYA | 78 | L 1-2 | 37-41 | 4 | 37,518 | Jason Johnson | David Cone | David Cone | Jason Johnson | Mariano Rivera | 425 | 442 | -17 |
| 1999-07-03 | @ NYA | 79 | L 5-6 | 37-42 | 4 | 42,859 | Sidney Ponson | Orlando Hernandez | Jason Grimsley | Arthur Rhodes | | 430 | 448 | -18 |
| 1999-07-04 | @ NYA | 80 | W 7-3 | 38-42 | 4 | 37,046 | Juan Guzman | Roger Clemens | Juan Guzman | Ramiro Mendoza | Scott Kamieniecki | 437 | 451 | -14 |
| 1999-07-05 | @ NYA | 81 | W 9-1 | 39-42 | 4 | 29,934 | Mike Mussina | Andy Pettitte | Mike Mussina | Andy Pettitte | | 446 | 452 | -6 |
| 1999-07-06 | vs TOR | 82 | L 3-4 | 39-43 | 4 | 37,939 | Scott Erickson | David Wells | Graeme Lloyd | Mike Timlin | Billy Koch | 449 | 456 | -7 |
| 1999-07-07 | vs TOR | 83 | L 6-7 | 39-44 | 4 | 42,275 | Jason Johnson | Joey Hamilton | Paul Spoljaric | Gabe Molina | Billy Koch | 455 | 463 | -8 |
| 1999-07-08 | vs TOR | 84 | L 6-11 | 40-44 | 4 | 41,738 | Sidney Ponson | Kelvim Escobar | Kelvim Escobar | Sidney Ponson | | 461 | 474 | -13 |
| 1999-07-09 | @ PHI | 85 | L 2-4 | 40-45 | 4 | 28,182 | Juan Guzman | Curt Schilling | Curt Schilling | Juan Guzman | | 463 | 478 | -15 |
| 1999-07-10 | @ PHI | 86 | W 8-4 | 41-45 | 4 | 32,300 | Mike Mussina | Paul Byrd | Mike Mussina | Paul Byrd | | 471 | 482 | -11 |
| 1999-07-11 | @ PHI | 87 | W 6-2 | 42-45 | 4 | 33,399 | Scott Erickson | Chad Ogea | Scott Erickson | Chad Ogea | | 477 | 484 | -7 |
| 1999-07-15 | vs MON | 88 | W 8-2 | 43-45 | 4 | 43,016 | Sidney Ponson | Mike Thurman | Sidney Ponson | Mike Thurman | | 485 | 486 | -1 |
| 1999-07-16 | vs MON | 89 | W 9-4 | 44-45 | 4 | 41,929 | Mike Mussina | Dan Smith | Mike Mussina | Dan Smith | | 494 | 490 | 4 |
| 1999-07-17 | vs MON | 90 | W 2-1 | 45-45 | 4 | 47,988 | Scott Erickson | Dustin Hermanson | Scott Erickson | Dustin Hermanson | | 496 | 491 | 5 |
| 1999-07-18 | vs NYN | 91 | L 6-8 | 45-46 | 4 | 47,480 | Juan Guzman | Masato Yoshii | Masato Yoshii | Juan Guzman | Armando Benitez | 502 | 499 | 3 |
| 1999-07-19 | vs NYN | 92 | L 1-4 | 45-47 | 4 | 42,615 | Jason Johnson | Octavio Dotel | Octavio Dotel | Jason Johnson | Armando Benitez | 503 | 503 | 0 |
| 1999-07-20 | vs NYN | 93 | W 4-1 | 46-47 | 4 | 45,450 | Sidney Ponson | Al Leiter | Sidney Ponson | Al Leiter | | 507 | 504 | 3 |
| 1999-07-21 | @ BOS | 94 | W 6-1 | 47-47 | 4 | 33,690 | Mike Mussina | Bret Saberhagen | Mike Mussina | Bret Saberhagen | | 513 | 505 | 8 |
| 1999-07-22 | @ BOS | 95 | W 5-2 | 48-47 | 4 | 33,605 | Scott Erickson | Jin Ho Cho | Scott Erickson | Jin Ho Cho | Mike Timlin | 518 | 507 | 11 |
| 1999-07-23 | vs ANA | 96 | W 1-0 | 49-47 | 4 | 43,945 | Juan Guzman | Jack McDowell | Juan Guzman | Jack McDowell | Mike Timlin | 519 | 507 | 12 |
| 1999-07-24 | vs ANA | 97 | W 8-4 | 50-47 | 4 | 48,544 | Jason Johnson | Ken Hill | Jason Johnson | Ken Hill | | 527 | 511 | 16 |
| 1999-07-25 | vs ANA | 98 | W 8-7 | 51-47 | 4 | 44,724 | Sidney Ponson | Chuck Finley | Scott Kamieniecki | Mike Holtz | | 535 | 518 | 17 |
| 1999-07-27 | vs TEX | 99 | L 6-8 | 51-48 | 4 | 42,949 | Mike Mussina | Aaron Sele | Aaron Sele | Mike Mussina | John Wetteland | 541 | 526 | 15 |
| 1999-07-28 | vs TEX | 100 | W 8-6 | 52-48 | 4 | 41,692 | Scott Erickson | John Burkett | Scott Erickson | John Burkett | Mike Timlin | 549 | 532 | 17 |
| 1999-07-29 | vs TEX | 101 | L 1-3 | 52-49 | 4 | 43,711 | Juan Guzman | Mike Morgan | Mike Morgan | Juan Guzman | John Wetteland | 550 | 535 | 15 |
| 1999-07-30 | @ SEA | 102 | L 4-7 | 52-50 | 4 | 44,931 | Jason Johnson | Gil Meche | Gil Meche | Jason Johnson | Jose Mesa | 554 | 542 | 12 |
| 1999-07-31 | @ SEA | 103 | L 2-5 | 52-51 | 4 | 45,139 | Sidney Ponson | Jamie Moyer | Jamie Moyer | Sidney Ponson | Jose Mesa | 556 | 547 | 9 |
| 1999-08-01 | @ SEA | 104 | L 1-3 | 52-52 | 4 | 45,149 | Mike Mussina | Jeff Fassero | Paul Abbott | Mike Mussina | Jose Mesa | 557 | 550 | 7 |
| 1999-08-02 | @ OAK | 105 | L 1-7 | 52-53 | 4 | 10,178 | Scott Erickson | Kevin Appier | Kevin Appier | Scott Erickson | | 558 | 557 | 1 |
| 1999-08-03 | @ OAK | 106 | L 2-12 | 53-53 | 4 | 10,878 | Ricky Bones | Tim Hudson | Tim Hudson | Ricky Bones | | 560 | 569 | -9 |
| 1999-08-04 | @ OAK | 107 | W 9-5 | 54-53 | 4 | 17,271 | Jason Johnson | Jimmy Haynes | Jason Johnson | Jimmy Haynes | | 569 | 574 | -5 |
| 1999-08-05 | vs DET | 108 | W 6-3 | 55-53 | 4 | 40,886 | Sidney Ponson | Jeff Weaver | Sidney Ponson | Jeff Weaver | Mike Timlin | 575 | 577 | -2 |
| 1999-08-06 | vs DET | 109 | L 3-4 | 55-54 | 4 | 41,708 | Mike Mussina | Dave Mlicki | Dave Mlicki | Mike Mussina | Todd Jones | 578 | 581 | -3 |
| 1999-08-07 | vs DET | 110 | W 5-4 | 56-54 | 4 | 48,505 | Scott Erickson | Dave Borkowski | Scott Erickson | Dave Borkowski | Mike Timlin | 583 | 585 | -2 |
| 1999-08-08 | vs DET | 111 | L 2-5 | 56-55 | 4 | 44,474 | Ricky Bones | Brian Moehler | Doug Brocail | Scott Kamieniecki | Todd Jones | 585 | 590 | -5 |
| 1999-08-09 | @ TBA | 112 | L 9-10 | 57-55 | 4 | 17,796 | Jason Johnson | Ryan Rupe | Ryan Rupe | Jason Johnson | Roberto Hernandez | 594 | 600 | -6 |
| 1999-08-10 | @ TBA | 113 | W 17-1 | 58-55 | 4 | 17,848 | Sidney Ponson | Dave Eiland | Sidney Ponson | Dave Eiland | | 611 | 601 | 10 |
| 1999-08-11 | @ TBA | 114 | W 4-2 | 59-55 | 4 | 17,824 | Mike Mussina | Rolando Arrojo | Mike Mussina | Rolando Arrojo | Mike Timlin | 615 | 603 | 12 |
| 1999-08-13 | @ CLE | 115 | L 3-6 | 59-56 | 4 | 43,073 | Scott Erickson | Charles Nagy | Ricardo Rincon | Scott Erickson | Michael Jackson | 618 | 609 | 9 |
| 1999-08-14 | @ CLE | 116 | L 1-7 | 59-57 | 4 | 43,103 | Jason Johnson | Steve Karsay | Steve Karsay | Jason Johnson | | 619 | 616 | 3 |
| 1999-08-15 | @ CLE | 117 | L 1-5 | 59-58 | 4 | 43,020 | Sidney Ponson | Bartolo Colon | Bartolo Colon | Sidney Ponson | | 620 | 621 | -1 |
| 1999-08-17 | vs MIN | 118 | W 8-3 | 60-58 | 4 | 40,485 | Mike Mussina | Joe Mays | Mike Mussina | Joe Mays | | 628 | 624 | 4 |
| 1999-08-18 | vs MIN | 119 | W 2-0 | 61-58 | 4 | 38,820 | Scott Erickson | LaTroy Hawkins | Scott Erickson | LaTroy Hawkins | | 630 | 624 | 6 |
| 1999-08-19 | vs MIN | 120 | W 9-3 | 62-58 | 4 | 38,320 | Jason Johnson | Dan Perkins | Jason Johnson | Dan Perkins | | 639 | 627 | 12 |
| 1999-08-21 | vs CHA | 121 | L 3-4 | 62-60 | 5 | 42,901 | Doug Linton | John Snyder | Bill Simas | Alberto Reyes | Bob Howry | 642 | 631 | 11 |
| 1999-08-21 | vs CHA | 122 | L 5-8 | 62-60 | 5 | 47,735 | Sidney Ponson | Mike Sirotka | Bob Howry | Doug Johns | Keith Foulke | 647 | 639 | 8 |
| 1999-08-22 | vs CHA | 123 | W 9-4 | 63-60 | 4 | 43,335 | Mike Mussina | Jaime Navarro | Doug Johns | Jaime Navarro | | 656 | 643 | 13 |
| 1999-08-23 | @ KCA | 124 | W 4-2 | 64-60 | 4 | 14,222 | Scott Erickson | Dan Reichert | Scott Erickson | Dan Reichert | Mike Timlin | 660 | 645 | 15 |
| 1999-08-24 | @ KCA | 125 | W 5-3 | 65-60 | 4 | 12,171 | Jason Johnson | Blake Stein | Scott Kamieniecki | Derek Wallace | Mike Timlin | 665 | 648 | 17 |
| 1999-08-25 | @ KCA | 126 | L 6-8 | 65-61 | 4 | 12,033 | Doug Linton | Jeff Suppan | Jeff Suppan | Doug Linton | Jeff Montgomery | 671 | 656 | 15 |
| 1999-08-26 | @ KCA | 127 | L 0-6 | 65-62 | 4 | 13,246 | Sidney Ponson | Jay Witasick | Jay Witasick | Sidney Ponson | | 671 | 662 | 9 |
| 1999-08-27 | @ DET | 128 | L 4-5 | 65-63 | 4 | 37,600 | Doug Johns | Jeff Weaver | Jeff Weaver | Alberto Reyes | Todd Jones | 675 | 667 | 8 |
| 1999-08-28 | @ DET | 129 | L 3-4 | 65-64 | 4 | 42,377 | Scott Erickson | Dave Mlicki | Dave Mlicki | Scott Erickson | Todd Jones | 678 | 671 | 7 |
| 1999-08-29 | @ DET | 130 | W 11-4 | 65-65 | 4 | 37,911 | Jason Johnson | C.J. Nitkowski | Jason Johnson | C.J. Nitkowski | | 689 | 675 | 14 |
| 1999-08-31 | vs TBA | 131 | L 0-3 | 65-66 | 4 | 36,223 | Sidney Ponson | Ryan Rupe | Ryan Rupe | Sidney Ponson | Roberto Hernandez | 689 | 678 | 11 |
| 1999-09-01 | vs TBA | 132 | W 3-1 | 66-66 | 4 | 37,009 | Doug Johns | Dan Wheeler | Doug Johns | Dan Wheeler | Mike Timlin | 692 | 679 | 13 |
| 1999-09-02 | vs TBA | 133 | W 11-6 | 66-67 | 4 | 39,172 | Scott Erickson | Rolando Arrojo | Scott Erickson | Rolando Arrojo | | 703 | 685 | 18 |
| 1999-09-03 | vs CLE | 134 | L 6-7 | 66-68 | 4 | 41,521 | Jason Johnson | Chris Haney | Paul Assenmacher | Alberto Reyes | Michael Jackson | 709 | 692 | 17 |
| 1999-09-04 | vs CLE | 135 | W 3-1 | 67-68 | 4 | 47,095 | Doug Linton | Bartolo Colon | Doug Linton | Bartolo Colon | Mike Timlin | 712 | 693 | 19 |
| 1999-09-05 | vs CLE | 136 | L 7-15 | 68-68 | 4 | 44,214 | Sidney Ponson | Dwight Gooden | Jim Brower | Sidney Ponson | | 719 | 708 | 11 |
| 1999-09-06 | vs CLE | 137 | L 6-7 | 68-69 | 4 | 40,540 | Doug Johns | Dave Burba | Dave Burba | Doug Johns | Michael Jackson | 725 | 715 | 10 |
| 1999-09-07 | @ MIN | 138 | W 5-0 | 69-69 | 4 | 9,263 | Scott Erickson | Joe Mays | Scott Erickson | Joe Mays | | 730 | 715 | 15 |
| 1999-09-08 | @ MIN | 139 | W 10-0 | 70-69 | 4 | 9,564 | Jason Johnson | LaTroy Hawkins | Jason Johnson | LaTroy Hawkins | | 740 | 715 | 25 |
| 1999-09-09 | @ MIN | 140 | W 6-5 | 71-69 | 4 | 9,903 | Matt Riley | Jason Ryan | Alberto Reyes | Travis Miller | Mike Timlin | 746 | 720 | 26 |
| 1999-09-10 | vs SEA | 141 | W 5-4 | 72-69 | 4 | 43,209 | Doug Linton | Paul Abbott | Alberto Reyes | Robert Ramsay | | 751 | 724 | 27 |
| 1999-09-11 | vs SEA | 142 | W 4-2 | 73-69 | 4 | 47,903 | Doug Johns | Freddy Garcia | Doug Johns | Freddy Garcia | Mike Timlin | 755 | 726 | 29 |
| 1999-09-12 | vs SEA | 143 | W 4-1 | 74-69 | 4 | 44,891 | Scott Erickson | John Halama | Scott Erickson | John Halama | | 759 | 727 | 32 |
| 1999-09-13 | vs SEA | 144 | W 5-4 | 75-69 | 4 | 40,756 | Sidney Ponson | Gil Meche | B.J. Ryan | Jose Mesa | | 764 | 731 | 33 |
| 1999-09-14 | vs OAK | 145 | W 13-6 | 75-70 | 4 | 40,789 | Mike Mussina | Mike Oquist | Mike Mussina | Mike Oquist | | 777 | 737 | 40 |
| 1999-09-17 | @ ANA | 146 | W 4-2 | 76-70 | 4 | 28,865 | Scott Erickson | Jarrod Washburn | Scott Erickson | Jarrod Washburn | Mike Timlin | 781 | 739 | 42 |
| 1999-09-18 | @ ANA | 147 | W 6-3 | 77-70 | 4 | 36,531 | Sidney Ponson | Brian Cooper | Sidney Ponson | Brian Cooper | Mike Timlin | 787 | 742 | 45 |
| 1999-09-19 | @ ANA | 148 | W 5-4 | 78-70 | 4 | 22,526 | Mike Mussina | Mike Fyhrie | Gabe Molina | Troy Percival | Mike Timlin | 792 | 746 | 46 |
| 1999-09-21 | @ TEX | 149 | W 4-2 | 79-70 | 4 | 24,192 | Jason Johnson | Esteban Loaiza | Jason Johnson | Esteban Loaiza | Mike Timlin | 796 | 748 | 48 |
| 1999-09-22 | @ TEX | 150 | W 7-4 | 80-70 | 3 | 34,007 | Scott Erickson | Rick Helling | Scott Erickson | Rick Helling | Mike Timlin | 803 | 752 | 51 |
| 1999-09-23 | vs OAK | 151 | L 6-9 | 80-72 | 5 | 0 | Sidney Ponson | Brett Laxton | T.J. Mathews | Gabe Molina | Jason Isringhausen | 809 | 761 | 48 |
| 1999-09-23 | vs OAK | 152 | W 12-4 | 80-72 | 5 | 43,778 | Matt Riley | Omar Olivares | Doug Johns | Omar Olivares | | 821 | 765 | 56 |
| 1999-09-24 | @ BOS | 153 | W 1-0 | 81-72 | 4 | 32,930 | Mike Mussina | Bret Saberhagen | Mike Mussina | Bret Saberhagen | Mike Timlin | 822 | 765 | 57 |
| 1999-09-25 | @ BOS | 154 | L 1-4 | 81-73 | 4 | 32,107 | Doug Linton | Ramon Martinez | Ramon Martinez | Doug Linton | Rich Garces | 823 | 769 | 54 |
| 1999-09-26 | @ BOS | 155 | W 8-5 | 82-73 | 4 | 32,115 | Jason Johnson | Tim Wakefield | Jason Johnson | Tim Wakefield | Jesse Orosco | 831 | 774 | 57 |
| 1999-09-27 | @ BOS | 156 | L 3-5 | 82-74 | 4 | 33,477 | Scott Erickson | Pedro Martinez | Pedro Martinez | Scott Erickson | Derek Lowe | 834 | 779 | 55 |
| 1999-09-28 | vs NYA | 157 | L 5-9 | 82-75 | 4 | 44,711 | Sidney Ponson | Ed Yarnall | Ramiro Mendoza | Sidney Ponson | | 839 | 788 | 51 |
| 1999-09-30 | vs NYA | 158 | W 5-0 | 83-75 | 6 | 44,568 | Mike Mussina | Roger Clemens | Mike Mussina | Roger Clemens | | 844 | 788 | 56 |
| 1999-09-30 | vs NYA | 159 | L 5-12 | 83-75 | 6 | 47,446 | Matt Riley | Orlando Hernandez | Orlando Hernandez | Jim Corsi | | 849 | 800 | 49 |
| 1999-10-01 | vs BOS | 160 | L 2-6 | 84-76 | 4 | 43,081 | Doug Linton | Bret Saberhagen | Tomo Ohka | Doug Linton | | 851 | 806 | 45 |
| 1999-10-02 | vs BOS | 161 | L 0-8 | 84-77 | 4 | 48,338 | Doug Johns | Ramon Martinez | Ramon Martinez | Doug Johns | | 851 | 814 | 37 |
| 1999-10-03 | vs BOS | 162 | L 0-1 | 84-78 | 4 | 47,567 | Scott Kamieniecki | Pat Rapp | Brian Rose | Mike Timlin | Tim Wakefield | 851 | 815 | 36 |